The subject matter disclosed herein relates to elevator systems driven by coated steel belts. More specifically, the subject disclosure relates to sheave configurations for elevator systems driven by coated steel belts.
Elevator systems utilize coated steel belts operably connected to an elevator car, and driven by a motor to propel the elevator car along a hoistway. Coated steel belts in particular include a plurality of wires located at least partially within a jacket material. The plurality of wires is often arranged into one or more strands and the strands are then arranged into one or more cords. In an exemplary belt construction, a plurality of cords is typically arranged equally spaced within a jacket in a longitudinal direction.
The motor drives a sheave, in this case a traction sheave, over which the coated steel belt is routed. The belt gains traction at the traction sheave, such that rotation of the traction sheave consequently drives movement of the elevator car. The coated steel belt is then routed over one or more idler or deflector sheaves to guide the belt between the traction sheave and the elevator car. It is desired for the belt to travel, or track, over a center portion of the deflector sheave to evenly distribute tension in the belt cords and to prevent cords, especially end cords, of the belt from going into compression and buckling. One method to center the belt on the deflector sheave is to incorporate a crown into the sheave surface geometry. A further requirement for the deflector sheave, however, is a low surface coefficient of friction in order reduce sticking or slipping of the belt over the deflector sheave and thereby reducing associated noise. If the deflector sheave coefficient of friction is too low, however, the belt will not have enough lateral traction to climb and remain at the crown.